The present invention relates to an elevator door drive device for opening and closing at least one car door leaf and at least one associated shaft door leaf of an elevator.
The present invention further relates to the problem of transmitting the opening and closing movement, which is produced by a car door drive, from at least one car door leaf to the associated shaft door leaf.
A door drive device with a coupling mechanism for coupling a card door leaf with an associated shaft door leaf has become known from European Patent Specification EP 0 332 841. The coupling mechanism comprises two entraining runners which are oriented to be parallel to the travel direction of the elevator car and which are adjustable in their mutual spacing by a parallelogram guide with two adjusting elements each pivotable about a respective pivot axis. If the elevator car is correctly disposed at a floor level, the two entraining runners lie between two coupling elements arranged adjacent to one another at the shaft door leaf and can be laterally guided up to these (spread) in order on the one hand to unlock the shaft door leaf and on the other hand to transmit the opening and closing movement of the car door to the car door leaf in play-free manner and synchronously. The adjustment of spacing between the two entraining runners in that case takes place by a door drive unit, which is fastened to the car door frame, by way of a linearly acting drive means (for example, by a belt drive), which also produces the closing and opening movements of the car door leaf. In that case the drive means so engages at the car door leaf by way of a pivot lever connected with the adjusting elements of the parallelogram guide that through the opening movement of the linearly acting drive means the adjusting elements are pivoted, before the start of a door leaf opening movement, into a setting in which the entraining runners are led up to the coupling elements, thereby unlock the shaft door leaf and form the said coupling between the car door leaf and the corresponding shaft door leaf.
At the end of the door leaf closing movement the adjusting elements are pivoted by the closing movement of the linearly acting drive means back into a setting in which the entraining runners are spaced from the coupling elements so that the locking of the shaft door leaf in its locked position returns.
In order to guarantee that the door leaf opening movement begins only when the entraining runners are fully spread and thus the shaft door leaf unlocked, a tension spring ensures that the spreading of the entraining runners takes place automatically even against the resistance of the shaft door unlocking. This has the consequence that at the start of the door opening process the drive means is driven by the tension spring in opening direction until the pivot lever is fully pivoted out in opening direction and that at the end of the closing process, i.e. on reversing the spreading of the entraining runners, the drive means has to work against the action of the relatively strong tension spring.
The door drive device shown in the EP 0 332 841 document has a number of disadvantages.
In order to ensure that on changeover the drive direction from the door leaf opening movement to the closing movement the adjusting elements are not prematurely pivoted back as a consequence of acceleration forces, i.e. the entraining runners do not space themselves from the coupling elements, the pivoting back of the pivot lever arranged between the drive means and one of the pivotable adjusting elements is prevented by a catch lever. This has the form of a double-armed, horizontally extending lever mounted at the door leaf. When the door leaf is disposed in its closed setting, the first arm of the catch lever lies on a support roller fastened to the car door frame and the second arm extends horizontally below an abutment dog which is present at the pivot lever and by way of which the drive means acts on the one adjusting element. The catch lever is so loaded with a torque about its fulcrum by a torsion spring that the second arm moves upwardly when the first arm is no longer supported. If the drive means at the beginning of the door leaf opening movement pivots the pivot lever together with the adjusting element in clockwise sense and thus has spread the entraining runners and subsequently the car door leaf has opened so far that the catch lever fastened thereto is no longer supported by the support roller, the second arm of the catch lever moves upwardly to the height of the abutment dog at the pivot lever and prevents the pivot lever and the adjusting element from pivoting back. Before, after reversal of the drive direction, the door leaf has reached the end of the closing movement the first arm of the catch lever is raised by the support roller, wherein the second arm moves downwardly and frees the abutment dog of the pivot lever so that the drive means can move the pivot lever, adjusting element and entraining runners into the initial setting in which the entraining runners are spaced from the coupling elements.
The disadvantages of this equipment are that the catch lever does not lock the pivot lever and the adjusting element in both pivot directions and does not lock them free of play. This can have the consequence on the one hand that the spacing between the spread entraining runners varies, which can have a negative effect on the unlocking process in the case of shaft doors and impairs the accuracy of the closing process in the case of the shaft doors, which can lead to the locking thereof not taking place correctly and triggering of a fault in operation. On the other hand, any play which is present, particularly in the case of rapidly moved and strongly accelerated door leaves, can produce disruptive noises.